| 1. |
- Kharrazi, Sogol, 1980, et al.
(författare)
-
Implementation of active steering on longer combination vehicles for enhanced lateral performance
- 2012
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 50:12, s. 1949-1970
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Tidskriftsartikel (refereegranskat)abstract
- A steering-based controller for improving lateral performance of longer combination vehicles (LCVs) is proposed. The controller steers the axles of the towed units to regulate the time span between the driver steering and generation of tyre lateral forces at the towed units and consequently reduces the yaw rate rearward amplification (RWA) and offtracking. The open-loop effectiveness of the controller is evaluated with simulations and its closed loop or driver in the loop effectiveness is verified on a test track with a truck-dolly-semitrailer test vehicle in a series of single-and double-lane change manoeuvres. The developed controller reduces the yaw rate RWA and offtracking considerably without diminishing the manoeuvrability. Furthermore, as a byproduct, it decreases the lateral acceleration RWA moderately. The obtained safety improvements by the proposed controller can promote the use of LCVs in traffic which will result in the reduction of congestion problem as well as environmental and economic benefits.
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| 2. |
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| 3. |
- Ardeshiri, Tohid, 1980, et al.
(författare)
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Sensor Fusion for Vehicle Positioning in Intersection Active Safety Applications
- 2006
-
Ingår i: 8th International Symposium on Advanced Vehicle Control. - 9860059470
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Global Positioning System (GPS) is being increasingly used in active safety applications. One field of active safety in which navigation information can be used is Intersection Active Safety Applications (IASA) which requires a precise and continuous estimate of vehicle position and heading direction to function properly. In this paper an implementation of Extended Kalman Filter for estimation of vehicle position and heading direction in an intersection active safety application is presented. The algorithm was tested on a complex urban trajectory of 2 km long and showed very encouraging results.
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| 4. |
- Arikere, Adithya, 1987, et al.
(författare)
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Integrated evasive manoeuvre assist for collision mitigation with oncoming vehicles
- 2018
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 56:10, s. 1577-1603
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Tidskriftsartikel (refereegranskat)abstract
- Development and deployment of steering based collision avoidance systems are made difficult due to the complexity of dealing with oncoming vehicles during the evasive manoeuvre. A method to mitigate the collision risk with oncoming vehicles during such manoeuvres is presented in this work. A point mass analysis of such a scenario is first done to determine the importance of speed for mitigating the collision risk with the oncoming vehicle. A characteristic parameter was identified, which correlates well with the need to increase or decrease speed, in order to reduce the collision risk. This finding was then verified in experiments using a Volvo XC90 test vehicle. A closed-loop longitudinal acceleration controller for collision mitigation with oncoming vehicles is then presented. The longitudinal control is combined with yaw stability control using control allocation to form an integrated controller. Simulations in CarMaker using a validated XC90 vehicle model and the proposed controller showed consistent reductions in the collision risk with the oncoming vehicle.
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| 5. |
- Arikere, Adithya, 1987, et al.
(författare)
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On the Potential of Accelerating an Electrified Lead Vehicle to Mitigate Rear-End Collisions
- 2015
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Ingår i: Proceedings of the 3rd International Symposium on Future Active Safety Technology Towards zero traffic accidents, 2015. ; , s. 377-384
-
Konferensbidrag (refereegranskat)abstract
- This paper analyzes the potential safety benefit from autonomous acceleration of an electrified lead vehicle to mitigate or prevent being struck from behind. Safety benefit was estimated based on the expected reduction in relative velocity at impact in combination with injury risk curves. Potential issues and safety concerns with the operation and implementation of such a system in the real world are discussed from an engineering and human factors stand point. In particular, the effect of the pre-collision acceleration in reducing whiplash injury risk due to change in head posture and reduction of crash severity is also discussed. In general, this study found that autonomously accelerating an electrified lead vehicle can mitigate and prevent rear-end collisions and significantly increase the safety benefits from existing systems such as autonomous emergency braking.
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| 6. |
- Arikere, Adithya, 1987, et al.
(författare)
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Speed control for reduced risk of collision with oncoming vehicles in obstacle avoidance scenarios
- 2016
-
Ingår i: Proceedings of the 13th International Symposium on Advanced Vehicle Control (AVEC’ 16), Munich, Germany, 13–16. - 9781138029927 ; , s. 37-42
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Konferensbidrag (refereegranskat)abstract
- When a driver performs an evasive steering manoeuvre in order to avoid an obstacle, there is an increased risk of collisions with oncoming vehicles in the adjacent lane. A controller to reduce this risk of secondary collision by regulating the vehicle speed is designed and implemented. Simulations are preformed in IPG CarMaker with the new Volvo XC90 vehicle model and performance of the controller are compared with more conventional lateral stability controllers and unassisted manoeuvres. While lateral control can be of benefit in some cases, it can hurt in others. When combined with speed control however, consistent reductions in risk of secondary collisions are seen and in cases involving large velocity ratios or long obstacles, large reductions are observed.
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| 7. |
- Arikere, Adithya, 1987, et al.
(författare)
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The Potential Safety Benefit of Propulsion in Obstacle Avoidance Manoeuvres with Oncoming Traffic
- 2014
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Ingår i: 12th International Symposium on Advanced Vehicle Control (AVEC '14), Tokyo Japan. ; , s. 126-131
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Konferensbidrag (refereegranskat)abstract
- The obstacle avoidance manoeuvre with oncoming traffic scenario is analysed. The possibility of using propulsion, specifically from electric motors, to reduce the risk of collision with oncoming traffic is investigated. Analysis is done using a point mass and a two track vehicle model in anoptimal control framework. It is found that propulsion can be of help in reducing the collision risk in such scenarios for a certain set of manoeuvre parameters.
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| 8. |
- Arikere, Adithya, 1987, et al.
(författare)
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The trade-off between distance margin and steering intrusiveness in obstacle avoidance manoeuvres with oncoming traffic
- 2016
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Ingår i: 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015; Graz; Austria; 17 August 2015 through 21 August 2015. - : CRC Press. ; , s. 243-252
-
Konferensbidrag (refereegranskat)abstract
- In this paper, the trade-off achieved between distance margin and steering intrusiveness in the obstacle avoidance manoeuvre with oncoming traffic scenario using different actuator sets is investigated. Investigation is first done using an optimal control framework to estimate the maximum benefit that can be achieved using the actuator sets. Next, closed loop controllers are used in simulation to estimate the benefit that can be obtained when the actuators are used for lateral control alone. It is found that for manoeuvres characterized by long obstacles and/or large bullet vehicle speeds relative to that of the host vehicle, torque vectoring can significantly reduce the risk of collision with an oncoming vehicle when compared to differential braking alone. It is found that it is beneficial to be able to perform safety interventions in this scenario with as little impact on the vehicle speed as possible which can be done by using a torque vectoring system.
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| 9. |
- Berbyuk, Viktor, 1953, et al.
(författare)
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Time-optimal control of semi-passively actuated closed-loop chain robots
- 2002
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Ingår i: Proceedings of the 33rd ISR (International Symposium on Robotics), October 7-11, 2002, Stockholm, Sweden, 2002. ; , s. 221-226
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Konferensbidrag (refereegranskat)abstract
- The controlled motions of a new structure of closed-loop chain robots with different degrees and types of actuation are under the study. An optimization approach has been used to investigate the advantages of using overactuation and unpowered spring-damper-like drives for the robots performing pick-and-place operations. Solution of several variants of a time-optimal control problem has been obtained for considered semi-passively actuated robots. Emphasis is put on the study of interaction between the controlling stimuli of powered drives and the torques exerted by unpowered drives needed to provide time-optimal motion of fully actuated and overactuated robots. Analysis of simulation results has shown that the quickness of the robots performing pick-and-place operations can be considerably increased due to overactuation and optimal dynamic interaction between powered and unpowered drives. Obtained results can be used for optimization of performance of robotic systems.
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| 10. |
- Chen, W., et al.
(författare)
-
Design and control of the steering torque feedback in a vehicle driving simulator
- 2018
-
Ingår i: The Dynamics of Vehicles on Roads and Tracks. ; 1, s. 213-220
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Konferensbidrag (refereegranskat)abstract
- Vehicle driving simulators allow engineers to evaluate subjectively the virtual prototype in early concept phase. Steering torque feedback as one of the basic haptic cues is usually provided by a servo motor through a force feedback system. The artificial feedback torque calculated from the vehicle model and sent to the servo motor is distorted by this interface. In this paper, it is investigated how the force feedback system dynamics influences the artificial steering feedback. To mask the dynamics of the force feedback system a feedforward compensation method based on the steering states has been proposed when driver is in the loop.
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| 11. |
- Chugh, Tushar, 1989, et al.
(författare)
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Design and control of model based steering feel reference in an electric power assisted steering system
- 2018
-
Ingår i: The Dynamics of Vehicles on Roads and Tracks. ; 1, s. 43-49
-
Konferensbidrag (refereegranskat)abstract
- Electric Power Assisted Steering (EPAS) system is a current state of the art technology for providing the steering torque support. The interaction of the steering system with the driver is principally governed by the EPAS control method. This paper proposes a control concept for designing the steering feel with a model based approach. The reference steering feel is defined in virtual dynamics for tracking. The layout of the reference model and the control architecture is discussed at first and then the decoupling of EPAS motor dynamics using a feedback control is shown. An example of how a change in steering feel reference (as desired by the driver) creates a change in steering feedback is further exhibited. The ultimate goal is to provide the driver with a tunable steering feel. For this, the verification is performed in simulation environment.
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| 12. |
- Gao, Yangyan, et al.
(författare)
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A flexible control allocation method for terminal understeer mitigation
- 2017
-
Ingår i: 2016 International Conference for Students on Applied Engineering (Icsae). ; , s. 18-23
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses the problem of terminal understeer of a road vehicle. The scenario is considered when a vehicle enters a curve with excessive speed and the aim is to apply automatic chassis control to prevent the vehicle from drifting out of the lane. In a previous study, the optimization problem is formulated as the minimization of maximum path off-tracking and the optimal response of a particle model is in the form of a parabolic path recovery (PPR) where the acceleration vector is fixed in the global frame. A recently developed model based control method the Modified Hamiltonian Algorithm (MHA) uses this acceleration information as a reference for control allocation to each wheel. The controller is developed using a simplified 3DOF vehicle model in Matlab and Simulink environment. In this paper, we consider using a high fidelity model in CarMaker to verify the control performance. It is of particular interest to see how well the chassis control can deal with the inherent understeer and oversteer qualities of the vehicle. Hence in this paper we evaluate the ability of an active safety system to overcome the mechanical limitations of the vehicle.
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| 13. |
- Gao, Yangyan, et al.
(författare)
-
An autonomous safety system for road departure prevention based on combined path and sideslip control
- 2016
-
Ingår i: The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015. - : CRC Press. - 9781138028852 ; , s. 281-286
-
Konferensbidrag (refereegranskat)abstract
- Practical limits on vehicle speed in curves depends on many factors: road friction, lateral maneuvering room, driving skill and the willingness of a driver to brakewhile cornering. This is in addition to multiple vehicle design and performance characteristics, including the classical understeer behaviour. The current paper considers an active safety control system to protect against the major effects of over-speed in curves, especially lateral drift leading to lane or road departure. The concept is to use available information about various vehicle and environmental factors-e.g. surface friction, lane and shoulder widths-and compute control interventions which will protect against lane and road departure. The proposed system is based on the optimal control of particle motions, as described previously for a Parabolic Path Reference (PPR) which provides a control reference for combined cornering and braking under computer control. The earlier work assumed very simple road geometry which is generalized in the present analysis. Further, we make use of a novel control algorithm based on nonlinear optimal control theory, capable of delivering the required integrated control of speed, path curvature and yaw stability. This paper describes the key concepts for designing and implementing such a system.
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| 14. |
- Gao, Y., et al.
(författare)
-
Implementation of a modified hamiltonian algorithm for control allocation
- 2017
-
Ingår i: Proceedings of the 13th International Symposium on dvanced Vehicle Control, AVEC 2016. - 9781315265285 ; 2017, s. 157-162
-
Konferensbidrag (refereegranskat)abstract
- This paper is motivated by the problem of terminal understeer of a road vehicle. A relevant scenario is where a vehicle enters a curve at excessive speed and the control objective is to apply automatic chassis control to prevent the vehicle from drifting out of the lane. In a previous study, the optimization problem was formulated as the minimization of maximum path off-tracking; the optimal response approximates to that of a friction-limited particle model, leading to a parabolic path reference (PPR) with the target mass-centre acceleration vector fixed in the global frame. The present paper considers in greater detail how the acceleration target is realized on an experimental vehicle. The approach is based on a recently developed model-based control method – the Modified Hamiltonian Algorithm (MHA). Simulations with a full vehicle (CarMaker) model are carried out, and test-track experiments are conducted to test the controller and validate the simulations. Results show that transient effects such as actuator delays and rate limits can have a significant effect on performance. On the other hand, the controller appears robust to factors such as tyre wear and uncertainty in vehicle parameters, and closely approximates the particle reference once these transient effects are accounted for. Since the control architecture is adaptive to track a changing acceleration reference, these conclusions are likely to be valid across a wider range of scenarios.
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| 15. |
- Gao, Yangyan, et al.
(författare)
-
Modified hamiltonian algorithm for optimal lane change with application to collision avoidance
- 2015
-
Ingår i: MM Science Journal. - : MM Publishing, s.r.o.. - 1805-0476 .- 1803-1269. ; :MAR 2015, s. 576-584
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with collision avoidance for road vehicles when operating at the limits of available friction. For collision avoidance, a typical control approach is to: (a) define a reference geometric path that avoids collision; (b) apply low-level control to perform path following. However, there are a number of limitations in this approach, which are addressed in the current paper. First, it is typically unknown whether a predefined reference path is feasible or over-conservative. Secondly, the control scheme is not well suited to avoiding a moving object, e.g. another vehicle. Further: incorrect choice of reference path may degrade performance, fast adaptation to friction change is not easy to implement and the associated low-level control allocation may be computationally intensive. In this paper we use the general nonlinear optimal control formulation, include some simplifying assumptions and base optimal control on the minimization of an underlying Hamiltonian function. A particle model is used to define an initial reference in the form of a desired global mass-center acceleration vector. Beyond that, yaw moment is taken into account for the purpose of enhancing the stability of the vehicle. The Hamiltonian function is adapted as a linear function of tyre forces and can be minimized locally for individual wheels; this significantly reduces computational workload compared to the conventional approach of forcemoment allocation. Several combinations of actuators are studied to show the general applicability of the control algorithm based on a linear Hamiltonian function. The method has the potential to be used in future vehicle control systems across a wide range of safety applications and hence improve overall vehicle agility and improve safety.
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| 16. |
- Gao, Yangyan, et al.
(författare)
-
Optimal control of brakes and steering for autonomous collision avoidance
- 2018
-
Ingår i: The Dynamics of Vehicles on Roads and Tracks. - 9781138035713 ; 1, s. 9-15
-
Konferensbidrag (refereegranskat)abstract
- This paper deals with collision avoidance for road vehicles when operating at the limits of available friction. We separate the control problem into two phases: collision avoidance phase and lane keeping phase. The aim is to reduce the amount of overshoot after avoiding the collision. The mass-center acceleration reference is obtained from a particle motion and implemented via a novel lower-level control allocation method, the Modified Hamiltonian Algorithm (MHA). At the upper level, we compared 3 common collision avoidance strategies with the proposed control strategy and determine trade-offs between the available intervention distance vs. overshoot during the lane keeping phase. It is found that the proposed control strategy has the least overshoot. MHA is found to achieve high quality tracking of the particle acceleration and it has performance close to that of the ideal particle. Yaw moment control, an integral part of MHA, is also found to be effective in maintaining yaw stability throughout.
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| 17. |
- Gao, Yangyan, et al.
(författare)
-
Optimal control of brakes and steering for autonomous collision avoidance using modified Hamiltonian algorithm
- 2019
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 57:8, s. 1224-1240
-
Tidskriftsartikel (refereegranskat)abstract
- This paper considers the problem of collision avoidance for road vehicles, operating at the limits of friction. A two-level modelling and control methodology is proposed, with the upper level using a friction-limited particle model for motion planning, and the lower level using a nonlinear 3DOF model for optimal control allocation. Motion planning adopts a two-phase approach: the first phase is to avoid the obstacle, the second is to recover lane keeping with minimal additional lateral deviation. This methodology differs from the more standard approach of path-planning/path-following, as there is no explicit path reference used; the control reference is a target acceleration vector which simultaneously induces changes in direction and speed. The lower level control distributes vehicle targets to the brake and steer actuators via a new and efficient method, the Modified Hamiltonian Algorithm (MHA). MHA balances CG acceleration targets with yaw moment tracking to preserve lateral stability. A nonlinear 7DOF two-track vehicle model confirms the overall validity of this novel methodology for collision avoidance.
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| 18. |
- Gordon, Tim, et al.
(författare)
-
Automated driving and autonomous functions on road vehicles
- 2015
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 53:7, s. 958-994
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, road vehicle automation has become an important and popular topic for research and development in both academic and industrial spheres. New developments have received extensive coverage in the popular press, and it may be said that the topic has captured the public imagination. Indeed, the topic has generated interest across a wide range of academic, industry and governmental communities, well beyond vehicle engineering; these include computer science, transportation, urban planning, legal, social science and psychology. While this follows a similar surge of interest - and subsequent hiatus - of Automated Highway Systems in the 1990s, the current level of interest is substantially greater, and current expectations are high. It is common to frame the new technologies under the banner of self-driving cars - robotic systems potentially taking over the entire role of the human driver, a capability that does not fully exist at present. However, this single vision leads one to ignore the existing range of automated systems that are both feasible and useful. Recent developments are underpinned by substantial and long-term trends in computerisation of the automobile, with developments in sensors, actuators and control technologies to spur the new developments in both industry and academia. In this paper, we review the evolution of the intelligent vehicle and the supporting technologies with a focus on the progress and key challenges for vehicle system dynamics. A number of relevant themes around driving automation are explored in this article, with special focus on those most relevant to the underlying vehicle system dynamics. One conclusion is that increased precision is needed in sensing and controlling vehicle motions, a trend that can mimic that of the aerospace industry, and similarly benefit from increased use of redundant by-wire actuators.
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| 19. |
- Gordon, Timothy James, 1953, et al.
(författare)
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Control Mitigation for Over-Speeding in Curves: Strategies to Minimize Off-Tracking
- 2012
-
Ingår i: Proceedings of the 11th International Symposium on Advanced Vehicle Control (AVEC '12).
-
Konferensbidrag (refereegranskat)abstract
- This paper tests the effectiveness of closed-loop brake control to reduce vehicle off-tracking arising from overspeedingin curves. When a driver enters a curve too fast given the available friction, the aim is to use electronicbrake control to reduce speed and increase path curvature to complete the turn. Previously it has been found thatcoordinated four wheel braking referenced to an inertially fixed vehicle mass center acceleration (PPR) is anoptimal control strategy. The present work introduces the effect of driver-vehicle interaction, using simulationand track experiments. It is confirmed that PPR effectiveness is not disrupted by typical steering correctionsfrom the driver. PPR is found to offer significant path following improvements compared with other brakecontrol strategies.
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| 20. |
- Gordon, Timothy James, 1953, et al.
(författare)
-
Experimental verification of understeer compensation by four wheel braking
- 2014
-
Ingår i: FISITA 2014 World Automotive Congress - Proceedings. ; 2014
-
Konferensbidrag (refereegranskat)abstract
- This study is designed to validate a new approach to understeer mitigation chassis control, based on a particlemotion reference: parabolic path reference (PPR). Considering the scenario of excess entry speed into a curve,related to run-off-road crashes, the aim is that automatic braking minimizes lateral deviation from the target pathby using an optimal combination of deceleration, cornering forces and yaw moments. Previous simulationstudies showed that four-wheel braking can achieve this much better than a conventional form of yaw momentcontrol (DYC). The aim of this work is to verify this on a test track with an experimental vehicle, and to compareperformance with DYC and an uncontrolled vehicle. Experiments were performed with a front-wheel-drivepassenger vehicle equipped with an additional four identical brake callipers controlled via an electro-hydraulicbrake (EHB) system, enabling individual brake control. Minimizing the maximum deviation from the intendedcurve radius is the control objective. Feedback to the controller consists of the available steering wheel angle,wheel speeds, yaw rate and lateral acceleration sensors in the vehicle. Additional to these variables, also thevehicle position was logged using a GPS system. It was found that PPR is superior to DYC in reducing themaximum deviation from the intended path, confirming the trends previously found in simulations. Furthermore,the PPR concept is found to be inherently more stable than DYC since more brake force is applied to the outerwheels than the inner wheels throughout the manoeuvre. The experiments involve a first implementation of aPPR control which is not a fully closed-loop control intervention and tuned to a step steer (transition fromstraight to fixed-radius curve. This is the first study to explicitly and systematically evaluate this new approachto understeer mitigation. The approach is fundamentally different from common DYC and suggests the potentialfor a new generation of controllers based on trajectory control via chassis actuators.
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| 21. |
- Hassanzadeh Siyahpoush, Morteza, 1980, et al.
(författare)
-
Path and speed control of a heavy vehicle for collision avoidance manoeuvres
- 2012
-
Ingår i: Intelligent Vehicles Symposium (IV), 2012 IEEE. Alcalá de Henares, Spain, 3-7 June 2012. - 1931-0587. - 9781467321198 ; , s. 129-134
-
Konferensbidrag (refereegranskat)abstract
- In an emergency situation prior to an imminent accident, first in-vehicle warning systems would intervene and aim to make the driver to take a suitable action. If the risk of accident was not eliminated, then an autonomous collision avoidance manoeuvre can prevent it. In this work, path and speed control are intended to be used to perform such a manoeuvre by using steering and braking actuators respectively. In order to provide actuators with suitable control inputs, first a path is planned for the heavy vehicle to follow during the manoeuvre. Then the path is used to calculate feedforward control inputs whereas a feedback controller assures the path tracking by compensating for errors. As a result, a robust path planning and control algorithm is designed and implemented that can perform autonomous collision avoidance manoeuvres for a heavy vehicle. Promising simulation results support ongoing works on vehicle demonstration and experiments on a real heavy vehicle.
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| 22. |
- Hemsen, Jonas, et al.
(författare)
-
Innovative and highly integrated modular electric drivetrain
- 2019
-
Ingår i: World Electric Vehicle Journal. - : MDPI AG. - 2032-6653. ; 10:4
-
Tidskriftsartikel (refereegranskat)abstract
- A highly integrated electric drivetrain module with 157 kW peak power is presented, which incorporates novel technologies in the field of electric machines, power electronics and transmissions: 1. High-speed electric machine with six phases and injection mould polymer-bonded magnets; 2. High-ratio dual-speed transmission with double planetary gear set (Ravigneaux gear set); 3. Gallium nitride (GaN) power electronics with winding reconfiguration feature. The combination of these components in one single housing makes the drive module flexible to integrate and to combine with conventional or alternative propulsion technologies, thus allowing various hybrid and electric drivetrain topologies. All technologies are selected in accordance with mass production potential and can therefore have a high impact on the automotive market in the future. Currently, the drive module is under development; the first models will be assembled in winter 2019. The integration into a demonstrator vehicle in 2020 will prove the potential of many new technologies and the suitability for the automotive market.
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| 23. |
- Jacobson, Bengt J H, 1962, et al.
(författare)
-
Potential effectiveness of a stability control system for passenger cars after an initial side impact
- 2014
-
Ingår i: FISITA 2014 World Automotive Congress - Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- Vehicle multiple-event accidents constitute 1/4-1/3 of all severe accidents. The present paper studies the control of the vehicle’s abnormal motion after being hit by another vehicle. The potential effectiveness of such a stability control system is estimated through accident data analysis and vehicle dynamics simulation. Only side impacts were simulated, but engineering judgments were made to project the effectiveness potential prediction on the total traffic work. Assuming ESC-like control (closed loop control on yaw rate, using wheel brakes) it is found that the function has potential to mitigate accident for up to 10-9 cars per driven km, or up to 0.1% of the cars in the accident database. While assuming Post Impact Stability Control by steering (closed loop control on yaw angle and path deviation, using steering), the corresponding figures are approximately ten times higher.
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| 24. |
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| 25. |
- Karyotakis, Konstantinos-Ektor, 1991, et al.
(författare)
-
Regenerative braking for an electric vehicle with a high-speed drive at the front axle
- 2021
-
Ingår i: Proceedings of the Resource Efficient Vehicles Conference - 2021 (rev2021). - 9789180400473 ; , s. 123-130
-
Konferensbidrag (refereegranskat)abstract
- The main contribution of this paper lies in the development of a novel front-to-rear axle brake force distribution strategy for the regenerative braking control of a vehicle with a high-speed electric drive unit at the front axle. The strategy adapts the brake proportioning to provide extended room for energy recuperation of the electric motor when the vehicle drivability and safety requirements permit. In detail, the strategy is adaptive to cornering intensity enabling the range to be further extended in real-world applications. The regenerative braking control features a brake blending control algorithm and a powertrain controller, which are decisive for enhancing the braking performance. Lastly, the regenerative braking control is implemented in the highfidelity simulation environment Simcenter Amesim, where system efficiency and regenerative brake performance are analysed. Results confirm that the designed regenerative braking greatly improves the effectiveness of energy recuperation for a front-wheel driven electric vehicle with a high-speed drive at the front axle. In conclusion, it is shown that it is feasible to use the high-speed drive with the proposed control design for regenerative braking.
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| 26. |
- Katzourakis, D. I., et al.
(författare)
-
Driver Steering Override for Lane-Keeping Aid Using Computer-Aided Engineering
- 2015
-
Ingår i: IEEE/ASME Transactions on Mechatronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1083-4435 .- 1941-014X. ; 20:4, s. 1543-1552
-
Tidskriftsartikel (refereegranskat)abstract
- The decreasing cost of radar and camera sensory technology has established advanced driver assistance systems (ADAS) to the standard equipment of modern vehicles. ADAS employ semi-autonomous interventions in longitudinal (e.g., adaptive cruise control, ACC) and lateral (e.g., lane-keeping aid, LKA) direction. ACC and LKA constitute the milestones of ADAS technology and have shown to correspondingly reduce driving effort and unintended lane-drifts. ADAS and driver share the vehicle control; this in-turn creates a nonfinite number of test cases that have to be tested-verified so-as to enable safe software (SW) release. Adjacent to ADAS, vehicle dynamics-related systems, such as the antilock braking system and the dynamic-stability and traction control, have also to undergo through an exhaustive SW verification. Distilling the previous statements, this paper cultivates the concept of virtual SW verification by evaluating Volvo's production and a concept driver steering override (DSO) for LKA systems. The DSO concept addresses the driver's interaction with the LKA system and adapts the intervention level. The driver's activation is quantified though the steering torque and road/vehicle information. Two different test-runs per DSO strategy are presented and the real-car (physical) testing results are reproduced in simulation. Both the real and postprocessed simulation results show: 1) the importance of the override strategy on the LKA benefits; and 2) the importance of computer-aided engineering for studying/designing ADAS.
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| 27. |
- Katzourakis, Diomidis, et al.
(författare)
-
Vehicle steering arrangement, autonomous vehicle steering arrangement, a vehicle, and a method of steering a vehicle
- 2018
-
Patent (övrigt vetenskapligt/konstnärligt)abstract
- A vehicle steering arrangement for a vehicle comprises a rack a position sensor, a steering column, a steering wheel, a torque sensor arranged to sense a torque applied onto the steering wheel and arranged to provide a torque signal representative thereof, an electronic control unit provided with a virtual steering model, a rack-mounted electromechanical actuator, and a force obtaining arrangement configured to obtain forces of steered wheels acting on the rack. The electronic control unit is configured to provide a virtual rack position based on the virtual steering model and at least a combination of the obtained forces and the torque signal, and is arranged to control the rack-mounted electromechanical actuator such that the current position of the rack is controlled towards the virtual rack position. The present disclosure also relates to an autonomous vehicle steering arrangement, a vehicle and a method of steering a vehicle.
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| 28. |
- Keshavarz Bahaghighat, Mansour, 1984, et al.
(författare)
-
Predictive Yaw and Lateral Control in Long Heavy Vehicles Combinations
- 2010
-
Ingår i: Proceedings of 49th IEEE Conference on Decision and Control. Atlanta, 15-17 December 2010. - 0191-2216. - 9781424477456 ; , s. 6403-6408
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of controlling the yaw and lateral dynamics in heavy vehicles, consisting of combina- tions of a truck and multiple towed units. In such heavy vehicle configurations, undesired yaw rate and lateral acceleration amplifications, causing tail swings and lateral instabilities of the towed units, can be observed at high speed.In this paper, we present a predictive control approach to reduce the Rearward Amplification (RWA) of the yaw rate at the rearmost unit in a truck-dolly-semitrailer combination, while bounding the lateral acceleration in order to prevent the roll-over of the rearmost unit. Simulation results with a nonlinear high fidelity vehicle model are presented in a single lane change maneuver, showing that the proposed approach is able to efficiently reduce the yaw rate RWA and limit the lateral accelerations, compared to the uncontrolled vehicle.
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| 29. |
- Kharrazi, Sogol, 1980, et al.
(författare)
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A generic controller for improving lateral performance of heavy vehicle combinations
- 2013
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 227:D5, s. 619-642
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Tidskriftsartikel (refereegranskat)abstract
- A generic controller for improving the lateral performance of heavy vehicle combinations by steering the axles of the towed units is proposed. The lateral performance of nine heavy vehicle combinations, including conventional combinations and existing and prospective longer combinations, are studied with and without the controller. The performance of the passive vehicles clearly indicates a need for improvements, which can be achieved by the proposed controller. The results obtained for controller verification in the frequency and time domains demonstrate that the controller reduces the yaw rate rearward amplification and off-tracking of all studied vehicles significantly, and diminishes trailer swings without reducing manoeuvrability. Furthermore, as a by-product, it moderately reduces the lateral acceleration rearward amplification. The improvements obtained by the proposed controller can promote the use of longer combination vehicles in traffic, which will result in a reduction of congestion, as well as substantial environmental and economic benefits.
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| 30. |
- Kharrazi, Sogol, 1980, et al.
(författare)
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Allocation of Braking and Steering Forces for Lateral Stability Control of a Heavy Vehicle Combination
- 2009
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Ingår i: Proceedings of the IAVSD'09 Conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Active steering and unilateral braking are two common methods to enhance lateral stability of heavy vehicle combinations. For optimal allocation of braking and steering forces to different axles of the vehicle combination, an understanding of their potential is required. In this study, effectiveness of active steering and unilateral braking of all the eight axles of a truck-dolly-semitrailer in diminishing a trailer swing under a lane change maneuver is investigated. The effectiveness is measured by the resulted reduction in the offtracking and rearward amplification. Each steering and braking intervention is applied as a constant input during a fixed time interval.
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| 31. |
- Kharrazi, Sogol, 1980, et al.
(författare)
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Improving Lateral Performance of Longer Combination Vehicles – An Approach Based on Eigenstructure Assignment
- 2012
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Ingår i: IEEE Intelligent Vehicles Symposium (IV), Alcala de Henares, Spain, 3-7 June 2012. - 9781467321198 ; , s. 328-333
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Konferensbidrag (refereegranskat)abstract
- Feasibility of eigenstructure assignment forcontrolling lateral performance of longer combination vehiclesis investigated. As a sample case, a controller is designed for a truck-dolly-semitrailer combination based on partialeigenstructure assignment and frequency response analysis.The results of simulations with a nonlinear vehicle model showsignificant improvement in lateral performance of the vehiclewith the designed controller.
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| 32. |
- Kharrazi, Sogol, 1980, et al.
(författare)
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Lateral stability control of a long heavy vehicle combination by active steering of the towed units
- 2010
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Ingår i: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC. - 9781424476572 ; , s. 168-173
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Konferensbidrag (refereegranskat)abstract
- A complete vehicle combination controller for enhancing the lateral stability of long heavy vehicle combinations by active steering of the towed units is presented. As a case study, the controller is developed for a truck-dolly-semitrailer combination and is evaluated in a sine with dwell maneuver, using a nonlinear model of this combination. The simulation results show a significant decrease in yaw rate rearward amplification and offtracking of the controlled vehicle.
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| 33. |
- Kharrazi, Sogol, 1980, et al.
(författare)
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Robustness analysis of a steering-based control strategy for improved lateral performance of a truck-dolly-semitrailer
- 2015
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Ingår i: International Journal of Heavy Vehicle Systems. - 1741-5152 .- 1744-232X. ; 22:1, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- A control strategy for lateral performance improvement of a truck-dolly-semitrailer combination by active steering of the towed units is presented. The effectiveness and robustness of the controller are verified by extensive analysis of the controller performance in various driving conditions at high speeds and presence of uncertainties in vehicle parameters, such as tyre cornering stiffness and moment of inertia. It is shown that the controller reduces the yaw rate rearward amplification, offtracking and side slip angle significantly. It is also demonstrated that brake interventions by other controlling systems such as electronic stability control do not deteriorate the controller performance.
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| 34. |
- Kharrazi, Sogol, 1980, et al.
(författare)
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The Effectiveness of Rear Axle Steering on the Yaw Stability and Responsiveness of a Heavy Truck
- 2008
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Ingår i: Vehicle System Dynamics. - 1744-5159 .- 0042-3114. ; 46:Supplement, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- Rear axle steering (RAS) at low speed is available in heavy trucks to improve their manoeuverability and reduce tyre wear; by extending the functionality of the existing RAS to high speed turning and split-mu braking, considerable safety benefits and enhancement in driver comfort can be gained. In this study, a RAS System was developed and simulated in Matlab–Simulink which showed encouraging results. Furthermore, the developed system was implemented on a Volvo Truck and tested in a series of split-mu braking and ISO double lane change manoeuvers. The obtained results conform to the expectations.
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| 35. |
- Klomp, Matthijs, 1976, et al.
(författare)
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On optimal recovery from terminal understeer
- 2014
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 228:4, s. 412-425
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the problem of terminal understeer and its mitigation via integrated brake control. The scenario considered is when a vehicle enters a curve at a speed that is too high for the tyre-road friction limits and an optimal combination of braking and cornering forces is required to slow the vehicle down and to negotiate the curve. Here, the driver commands a step steering input, from which a circular arc reference path is inferred. An optimal control problem is formulated with an objective to minimize the maximum off-tracking from the reference path, and two optimal control solutions are obtained. The first is an explicit analytical solution for a friction-limited particle; the second is a numerically derived open-loop brake control sequence for a nonlinear vehicle model. The particle solution is found to be a classical parabolic trajectory associated with a constant acceleration vector of the global mass center. The independent numerical optimization for the vehicle model is found to approximate closely the kinematics of the parabolic path reference strategy obtained for the particle. Using the parabolic path reference strategy, a closed-loop controller is formulated and verified against the solution from numerical optimization. The results are further compared with understeer mitigation by yaw control, and the parabolic path reference controller is found to give significant improvement over yaw control for this scenario.
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| 36. |
- Klomp, Matthijs, 1976, et al.
(författare)
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Optimal Path Recovery for a Vehicle Tracking a Circular Reference Trajectory
- 2010
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper addresses the problem of path recovery when the speed is too high to permit successful tracking of a circular reference trajectory. The optimal path recovery is formalized as an optimal control problem: to minimize the maximum off-tracking from the desired path. The essential element of the present approach is in the allocation of resultant vehicle forces derived from a simple particle representation. In this case the optimal path recovery is shown to be a classical parabolic trajectory resulting from a constant target acceleration vector. The proposed method yields significantly different outcomes when compared to the more commonly cited yaw moment allocation for understeer mitigation. A performance comparison is made between the two approaches, and the parabolic reference method results in approximately one half the off-tracking of the yaw-moment allocation algorithm. Some generalizations of the problem are also considered, namely non-isotropic friction limits and the use of a spiral reference trajectory.
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| 37. |
- Klomp, Matthijs, 1976, et al.
(författare)
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Safety Margin Estimation in Steady State Maneuvers
- 2006
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Ingår i: 8th International Symposium on Advanced Vehicle Control. - 9860059470
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper suggests a metric defining the margin of the actual longitudinal speed to a speed at which eitherthe front or rear tires reach saturation. This margin is referred to as the safety margin of the vehicle. It isshown that this safety margin is particularly useful for systems that use continuous yaw-rate errorelimination, such as advanced AWD systems. The proposed safety margin was evaluated using computersimulations.
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| 38. |
- Kraft, Karin, 1977, et al.
(författare)
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Using an adaptive FEM to determine the optimal control of a vehicle during a collision avoidance manoeuvre
- 2007
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Ingår i: Linköping Universtity Electronic Press. - 1650-3740. ; 27:15
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Konferensbidrag (refereegranskat)abstract
- The optimal manoeuvering of a vehicle during a collision avoidance manoeuvre is investigated. A basic model where the vehicle is modelled by a mass-particle and the mathematical formulation of the optimal manoeuvre are presented. The resulting two-point boundary problem is solved by an adaptive finite element method and the theory behind this method is described.
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| 39. |
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| 40. |
- Levén, Michael, 1988, et al.
(författare)
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Derivation of linear single-track truck-dolly-semitrailer model with steerable axles
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We consider a linear single-track model of a truck-dolly-semitrailer by deriving Lagrange's equations withthe quasi-coordinates chosen as the body fixed longitudinal and lateral velocity of the truck, vx1 and vy1,respectively, the yaw angle of the truck and the articulation angles of the dolly and the semi-trailer. The linear analysis and simulations arecarried out with a constant longitudinal velocity of 80 Kph for the passive vehicle, i.e. no steering on the dollyor semitrailer. The analysis shows an increase in yaw rate gain for the dolly and semitrailer, compared to thetruck, for frequencies around 0.4 Hz on the truck steering angle. That is, we have a yaw rate RWA higherthan 1 when for frequencies around 0.4 Hz. We also observe a lateral acceleration gain, between 0.1 and 1 Hz,for the dolly and semitrailer. Moreover, the phase angle has a higher frequency dependence for the dolly andsemitrailer both for yaw rate and lateral acceleration. Time simulations shows that the dolly and semitrailerexperience a time delay and an overshoot when the vehicle combination is subjected to various steering anglemaneuvers. This indicates that the vehicle combination is not as stable as the truck alone.
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| 41. |
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| 42. |
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| 43. |
- Lidberg, Mathias R, 1970
(författare)
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Design of Optimal Control Processes for Closed-Loop Chain SCARA-Like Robots
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The design of optimal control processes for closed-loop chain SCARA-like robots is the subject of this thesis. In comparison with the well-known SCARA robot, the proposed new structure is characterized by the incorporation of an additional powered actuator, several unpoweredactuators and an additional link that gives a closed-loop chain robot. The performance of the SCARA-like robot with various arrangements of powered and unpowered actuators isaddressed by formulating and solving energy-optimal and time-optimal control problems for periodic pick-and-place operations in the horizontal plane. Two computational methods suitable for solving optimal control problems for two-degree-of-freedom closed-loop chain SCARA-like robots are developed. With the direct parameter optimization approach, the relevant optimal control problems are converted into nonlinear programming problems using an inverse dynamics based method with polynomial-Fourierseries approximation of the generalized coordinates and the redundant torques. The resulting constrained nonlinear optimization problems are solved using sequential quadraticprogramming (SQP). An indirect computational method based on Pontryagins maximum principle is also developed. The necessary conditions of optimality are derived for the problems considered, and the resulting multi-point boundary-value problems are solved with a smoothing-continuation approach and an adaptive collocation method.In closed-loop chain robots with more actuators than degrees-of-freedom (overactuation), the dynamic redundancy enables optimization of the force distribution. Unpowered spring-like drives can assist the powered actuators or control some of the degrees-of-freedom of a manipulator robot (semi-passive control). Here, the advantages of overactuation and semi-passive control for the SCARA-like robots are demonstrated analytically and numerically forboth given motion and periodic pick-and-place operations.The numerical results for the solutions to the energy-optimal control problems show that the energy consumption and maximum torque required of the active actuators for typical pick-and-place operations can be reduced by using overactuation or adding unpowered drives to the structure of the robot. Using semi-passive control of the SCARA-like robot also allows simplification of the control system by reducing the number of powered actuators (underactuation). The results from the time-optimal control problems confirm the advantages of overactuation and semi-passive control.The results obtained in this thesis suggest that other mechanical systems and machines with periodic motion, such as various robots, automatic cyclic machines and bipedal robots, can benefit from overactuation and semi-passive control.
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| 44. |
- Lidberg, Mathias R, 1970, et al.
(författare)
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Directional Stability of a Front Wheel Drive Passenger Car with Preemptive Use of the Direction Sensitive Locking Differential (DSLD)
- 2020
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Ingår i: Lecture Notes in Mechanical Engineering. - Cham : Springer International Publishing. - 2195-4356 .- 2195-4364. ; , s. 1271-1277
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Konferensbidrag (refereegranskat)abstract
- The topic of this paper is the bigger picture of vehicle dynamics and handling characteristics of cars, with a focus on driving safety. More specifically, the directional stability gain obtained using the semi-active differential (DSLD) is experimentally verified in transient steering maneuvers using a prototype in a FWD Saab 9-3 Aero. Stemming from the obvious need to enable low speed maneuvering, the open differential was developed already in the beginning of the automotive era and it has ever since maintained a position as the unquestioned solution almost irrespective of the driving situation. However, due to the inherent compromise between low speed maneuverability and high speed stability in road vehicle design, there are fundamental benefits of locking the differential more or less preemptively during for example expressway driving. In recent decades electronic stability control (ESC) has become the go-to solution to improve driving safety by increasing the directional stability in transient maneuvers. However, similar but significantly greater stability gains can be accomplished by utilizing controllable differentials. All in all this means that the mentioned inherent compromise between maneuverability and stability can be circumvented and the overall handling characteristics of cars can be fundamentally improved.
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| 45. |
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| 46. |
- Lidberg, Mathias R, 1970, et al.
(författare)
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Energy-optimal control of semi-passively actuated SCARA-like robot
- 2002
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Ingår i: Proceedings of the First International Symposium on Mechatronics, (Eds: Peter Maisser and Peter Tenberge), March 21-22, 2002, Chemnitz, Cermany. - 3000075046 ; , s. 302-311
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Konferensbidrag (refereegranskat)abstract
- The optimal control of a new structure of manipulator robot is under study. In comparison with the well-known SCARA robot the proposed robotic system has severalunpowered (passive) spring-damper-like drives. An additional link has also been incorporated into the structure that gives the possibility to obtain a semi-passively actuated closed-loop chain robot. Energy-optimal motion of the robot is under study for the periodic pick-and-place operations. To design the optimal control of the robot a polynomial-Fourier series approximation of the independent variable functions and a sequentialquadratic programming method have been used. We are in particular studying the sensitivity of the kinematic, dynamic and energetic characteristics of the obtainedoptimal motion of the robot with respect to the parameters of the passive drives and the degree of actuation of the system.
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| 47. |
- Lidberg, Mathias R, 1970, et al.
(författare)
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Modeling of controlled motion of semi-passively actuated SCARA-like robot
- 2000
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Ingår i: Proceedings of the 7th Mechatronics Forum International Conference, 6-8 September 2000, Atlanta, Georgia, USA, PERGAMON, 2000.. - 0080437036
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The controlled motion of a new structure of manipulator robot is under study. In comparison with the well-known SCARA robot the proposed robotic system has the following new features: in addition to powered drives it comprisesseveral unpowered (passive) spring-damper-like drives. An additional link has also been incorporated into the structure that gives the possibility to obtain a semipassively actuated closed-loop chain robot. Special emphasis is put on a study of the interaction between the controlling stimuli of the powered drives and the torquesexerted by the unpowered drives needed to provide the energy-optimal motion of the robot. Computer simulations have demonstrated the numerical efficiency of thedeveloped algorithms and have proved several advantages of the considered semipassively actuated closed-loop robot.
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| 48. |
- Lidberg, Mathias R, 1970, et al.
(författare)
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Optimisation of controlled motion of closed-loop chain manipulator robots with different degree and type of actuation
- 2002
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Ingår i: J. Stability and Control: Theory and Application, (SACTA).. - 1563-3276. ; 4:2, s. 56-73
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Tidskriftsartikel (refereegranskat)abstract
- A number of energy-optimal control problems for a new structure of closed-loop manipulator robot are considered. We present methodology and algorithm that is suitable for solving optimization problems for manipulator robots with different degree and type of actuation. This methodology isbased on polynomial and Fourier series approximation of independently varying functions and conversion of the initial optimal control problem into the constrained parameter optimization problem. The methodology has been successfully used for optimization of under-, fully-, and overactuated robots having both external (powered) drives and internal (unpowered or passive) spring-damper-like drives. Comparison analysis of the simulation results of the obtained energy-optimal control processes fordifferent manipulator robots is presented.
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| 49. |
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| 50. |
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